A physical change refers to a type of change in matter where the substance involved does not undergo a chemical reaction and hence its identity remains unchanged. In a physical change, the molecular structure of the substance is altered, but its chemical composition remains the same. Physical changes are usually reversible. Some examples of physical changes include changes in shape, size, texture, state of matter (solid, liquid, gas), color, temperature, and density. For instance, when ice melts and turns into water, it is a physical change as the substance remains H2O molecules, just in a different state. Similarly, when a piece of paper is crumpled, it undergoes a physical change in its shape, but the paper itself remains the same substance.
